It has been known for a long time to make such shaped parts as bearing cages for rolling bearings. In a first step, pockets for receiving rolling elements are made in a flat metal strip by punching. A suitable length for accommodating the desired cage diameter is cut from the metal strip and rolled into a cylindrical shape so that the two joint edges of the strip touch each other. To finish the cage, the adjoining joint edges are then connected to each other by welding (DE 15 52 099).
A drawback of this method is that the joint welding results in the formation of welding mounds that have to be removed in a subsequent work step because, otherwise, they can damage the bearing. A further drawback is that so-called interruptions occur due to joint welding. These interruptions are to be understood as inwardly extending geometric irregularities that can occur in different gradations. The spectrum of the interruptions begins within the surface roughness and ends in a depth in which the interruptions can have a detrimental effect on the operation of the component i.e., in the extreme case, the component can become unserviceable. Such interruptions produce a notch effect i. e., due to the sudden change of the cross-section or of the surface contour, they cause a disturbance in the even flow of force in the component. A concentration of stress is produced at these notches and a stress peak is formed at the notch root. This notching is attended by two effects. Firstly, the load-bearing cross-section is reduced and, secondly, loading is concentrated at the notch root. This notch effect within the weld joint between the two joint edges of the cage has a particularly negative influence on the fatigue strength of the cage under high load conditions.